Dear Tom,
We needed to address some of the issues you identify here in developing ISO
15926 (in particular ISO 15926-2:2003). This standard is intended to support
the sharing and integration of data across the process plant life-cycle and
across organizations/systems. This means that design data created by a
design contractor might be copied to an owner operator, with updates etc.
Other data might come from equipment suppliers, and might be shared with
government bodies, and eventually demolition contractors. Whilst the
architecture supported a distributed database over the internet, it also
assumed that copies of data might need to be kept locally. The data model
developed was able to support:
- when the original data was created (and by whom),
- when the copy in the current database was created,
- what the identifier for the object is in this database,
- how the object is identified in some (any) other database. (01)
Regards (02)
Matthew West
Information Junction
Mobile: +44 750 3385279
Skype: dr.matthew.west
matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
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Registered office: 8 Ennismore Close, Letchworth Garden City, Hertfordshire,
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-----Original Message-----
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of John F Sowa
Sent: 17 May 2015 18:52
To: ontolog-forum@xxxxxxxxxxxxxxxx
Subject: [ontolog-forum] On Ontologies, Times, and Persons (was second
attempt...) (04)
Tom and Joe, (05)
I changed the subject line to the title of Tom's .doc file (which I copied
below as plain text). (06)
Tom
> Is anyone doing any work on this topic? (07)
Brief answer: Yes, many people in many scattered locations with many
similar, but independently developed methods. Some of them are included
among the 100+ documents I cited in the web page on "Semantics for
Interoperable Systems": http://www.jfsowa.com/ikl (08)
Joe
> We are expanding the work of John N. Warfield and others to include
> some of the features (09)
Do you have any articles or slides about that work? Amazon has a book by
Warfield for $102. But it seems to have a lot of overlap with the following
"Handbook of Interactive Management", which you can download for free:
http://demosophia.com/wp-content/uploads/2012/09/Handbook-of-Interactive-Man
agement.pdf (010)
Tom
> a distinction common in logic, the distinction between statements and
> propositions. A proposition is the semantic content of a set of
> synonymous statements. (011)
One of the articles cited on that page defines a proposition as an
equivalence class of sentences that are related by a "meaning preserving
translation" (MPT). That definition was adopted for the definition of
'proposition' in the IKL logic. See
http://www.jfsowa.com/logic/proposit.htm (012)
Tom
> I think it must be the case that different ontologies, as sets of
> different statements, can express the same ontology, as a set of
> propositions. (013)
Yes. Any ontology can be considered a single sentence, namely the
conjunction of all the sentences in it. Therefore, two ontologies can be
considered "the same" iff there is an MPT that groups them in the same
equivalence class. (014)
In principle, that "solves" the problem. But in practice, that is just the
beginning of a very hard problem. (015)
There is much more to be said on all these issues. The documents cited in
IKL cover many of the issues, and I'm always happy to add more. (016)
John
_______________________________________________________________________ (017)
On Ontologies, Times and Persons (018)
by Tom Johnston, May 17, 2015 (019)
As many of you know, I'm interested in managing temporal data in commercial
databases, and have recently developed an ontology which I think is common
to all such databases. (020)
One of the topics I still have a lot of work to do on is that of the
temporalization, and other relativizations, of formal ontologies themselves. (021)
At one level, a formal ontology is expressed in a set of data structures and
instances of those structures. Let's call this the "inscriptional level". If
a formal ontology, call it Ont-X, exists on one computer and then is copied
to another computer, there then exists a second inscription of that
ontology. A branching process can lead to a tree of inscriptions of Ont-X. (022)
And as in biological evolution, or in the copying of manuscripts, errors can
be introduced in the copying process. Sometimes it might be important to
track down a particular error, and so it would be useful to keep track of
the provenance of those inscriptions of Ont-X. (023)
Is anyone doing any work on this topic? (024)
But this is just the issue of the temporalization of inscriptions of the
same ontology. What about the evolution of that ontology itself -- that
ontology as the semantics common to all those inscriptions? I consider this
distinction to be precisely the distinction between a statement and the
possibly many inscriptions of that statement. (025)
So, as a semantic object, Ont-X may evolve over time. At times t1 and t2,
the ontological commitments expressed in Ont-X may differ. (Let's assume
that Ont-X remained semantically stable between t1 and t2). (026)
Call the two ontologies Ont-X1 and Ont-X2. So there is a semantic provenance
also, in this case that the same ontology was originally Ont-X1, and later
became Ont-X2. (027)
Now note the apparent inconsistency (intentional). I referred in the same
sentence to "two ontologies" and to "the same ontology". The inconsistency
is a simple terminological matter, I think. Because X1 and
X2 express different ontological commitments, it seems most natural to call
them different ontologies. But because X2 was created from X1, by making
some changes to X1, it is also possible to think of an ontology
-- Ont-X -- as an enduring semantic object that has changed over time, that
X1 is an earlier state of X and X2 a later successor state. (028)
It seems to me that this, too, is something worth keeping track of.
Is anyone doing work on this topic? (029)
Now consider two ontologies -- Ont-X and Ont-Y. Suppose that by means of
some intuitively natural translations, we find that X and Y, at the same
point in time, express the same ontology. What, in this context, does "same
ontology" mean? (030)
Again, I analyze this by means of a distinction common in logic, the
distinction between statements and propositions. A proposition is the
semantic content of a set of synonymous statements. We now have a
many-to-one relationship between inscriptions and statements, and next a
many-to-one relationship between statements and propositions. (031)
This is a harder problem than the first one. But just as we know that "John
loves Mary" and "Mary is loved by John" are two statements that express the
same proposition, I think it must be the case that different ontologies, as
sets of different statements, can express the same ontology, as a set of
propositions. (032)
Of course, this is indeed a very hard problem. And because of my lack of
familiarity with the work done by ontology engineers, I can ask a third
question: is anyone doing work on this topic? (033)
Now a final question. Just as there is a distinction between a statement and
an assertion by one or more persons, at a time t, that the statement is (or
is not) true, and also between a proposition and an assertion by one or more
persons, at a time t, that the proposition is (or is not) true, there must
be a distinction between an ontology as a set of statements, or even as a
set of propositions, and an assertion by one or more persons that the
ontology does or does not express their own ontological commitments. (034)
(A redundancy here: to assert that a statement is true is to assert that the
proposition expressed by the statement is true. But no matter, I think, for
this discussion.) (035)
And here the provenance to be tracked is an evolving set of ontological
commitments, by a specific person or group of persons, at a point in time or
over a period of time. As the expression of a set of ontological
commitments, then, an ontology is in fact relativized to a time t and a
person p. And just as a "language" is derivative from its component
dialects, and a dialect from its component idiolects, and an idiolect as
something that varies, for the person whose idiolect it is, over time, a
formal ontology, as the expression of a set of ontological commitments, is
too. (036)
People can make assertions and later withdraw them. They can express other
propositional attitudes, as well, such as doubt, approbation or
disapprobation, and so forth. And since the same person can change
propositional attitude towards the same propositions, and since the same
proposition can be asserted by one person at time t and denied by another
person at time t, there is an at least two-dimensional space in which formal
ontologies, as expressions of ontological commitments, can exist and move
about. (037)
(If we represent specific propositional attitudes as a dimension, then we
have a three-dimensional space.) (038)
Once more, is anyone working on this topic? (039)
Regards to all.
Tom Johnston (040)
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